Compilare: main.cpp: In function 'ull fact(int)': main.cpp:49:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(ull i = 2; i <= n; i++) rez *= i; ~~^~~~ main.cpp: In function 'int main()': main.cpp:55:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("sumall.in", "r", stdin); ^ main.cpp:56:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("sumall.out", "w", stdout); ^ main.cpp:59:22: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%llu", &n); ^